Allow descendant chains to simultaneously be hovered.

Matches GV behaviour. Also fixes a bug in QSGMouseArea,
which we aren't fixing for QtQuick 1.

Task-number: QTBUG-18175
Change-Id: I4ecac7b908504f28de830732c731281407d7b0bc
Reviewed-on: http://codereview.qt.nokia.com/2422
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>

6 files changed, 140 insertions, 27 deletions

diff --git a/src/declarative/items/qsgcanvas.cpp b/src/declarative/items/qsgcanvas.cpp
index ecb4e2b524..2efdd50c73 100644
--- a/src/declarative/items/qsgcanvas.cpp
+++ b/src/declarative/items/qsgcanvas.cpp
@@ -422,7 +422,6 @@ QSGCanvasPrivate::QSGCanvasPrivate()
     : rootItem(0)
     , activeFocusItem(0)
     , mouseGrabberItem(0)
-    , hoverItem(0)
     , dirtyItemList(0)
     , context(0)
     , contextFailed(false)
@@ -955,17 +954,19 @@ QSGItem *QSGCanvas::mouseGrabberItem() const
 }
 
 
-void QSGCanvasPrivate::clearHover()
+bool QSGCanvasPrivate::clearHover()
 {
     Q_Q(QSGCanvas);
-    if (!hoverItem)
-        return;
+    if (hoverItems.isEmpty())
+        return false;
 
     QPointF pos = q->mapFromGlobal(QCursor::pos());
 
-    QSGItem *item = hoverItem;
-    hoverItem = 0;
-    sendHoverEvent(QEvent::HoverLeave, item, pos, pos, QApplication::keyboardModifiers(), true);
+    bool accepted = false;
+    foreach (QSGItem* item, hoverItems)
+        accepted = sendHoverEvent(QEvent::HoverLeave, item, pos, pos, QApplication::keyboardModifiers(), true) || accepted;
+    hoverItems.clear();
+    return accepted;
 }
 
 
@@ -1205,11 +1206,7 @@ void QSGCanvas::mouseMoveEvent(QMouseEvent *event)
         bool delivered = d->deliverHoverEvent(d->rootItem, event->pos(), last, event->modifiers(), accepted);
         if (!delivered) {
             //take care of any exits
-            if (d->hoverItem) {
-                QSGItem *item = d->hoverItem;
-                d->hoverItem = 0;
-                accepted = d->sendHoverEvent(QEvent::HoverLeave, item, event->pos(), last, event->modifiers(), accepted);
-            }
+            accepted = d->clearHover();
         }
         event->setAccepted(accepted);
         return;
@@ -1247,20 +1244,43 @@ bool QSGCanvasPrivate::deliverHoverEvent(QSGItem *item, const QPointF &scenePos,
     if (itemPrivate->hoverEnabled) {
         QPointF p = item->mapFromScene(scenePos);
         if (QRectF(0, 0, item->width(), item->height()).contains(p)) {
-            if (hoverItem == item) {
+            if (!hoverItems.isEmpty() && hoverItems[0] == item) {
                 //move
                 accepted = sendHoverEvent(QEvent::HoverMove, item, scenePos, lastScenePos, modifiers, accepted);
             } else {
-                //exit from previous
-                if (hoverItem) {
-                    QSGItem *item = hoverItem;
-                    hoverItem = 0;
-                    accepted = sendHoverEvent(QEvent::HoverLeave, item, scenePos, lastScenePos, modifiers, accepted);
+                QList<QSGItem*> parents;
+                QSGItem* parent = item;
+                parents << item;
+                while ((parent = parent->parentItem()))
+                    parents << parent;
+
+                //exit from previous (excepting ancestors)
+                while (!hoverItems.isEmpty() && !parents.contains(hoverItems[0])){
+                    sendHoverEvent(QEvent::HoverLeave, hoverItems[0], scenePos, lastScenePos, modifiers, accepted);
+                    hoverItems.removeFirst();
                 }
 
-                //enter new item
-                hoverItem = item;
-                accepted = sendHoverEvent(QEvent::HoverEnter, item, scenePos, lastScenePos, modifiers, accepted);
+                if (!hoverItems.isEmpty() && hoverItems[0] == item){//Not entering a new Item
+                    accepted = sendHoverEvent(QEvent::HoverMove, item, scenePos, lastScenePos, modifiers, accepted);
+                } else {
+                    //enter any ancestors that also wish to be hovered and aren't
+                    int startIdx = -1;
+                    if (!hoverItems.isEmpty())
+                        startIdx = parents.indexOf(hoverItems[0]);
+                    if (startIdx == -1)
+                        startIdx = parents.count() - 1;
+
+                    for (int i = startIdx; i >= 0; i--) {
+                        if (QSGItemPrivate::get(parents[i])->hoverEnabled) {
+                            hoverItems.prepend(parents[i]);
+                            sendHoverEvent(QEvent::HoverEnter, parents[i], scenePos, lastScenePos, modifiers, accepted);
+                        }
+                    }
+
+                    //enter new item
+                    hoverItems.prepend(item);
+                    accepted = sendHoverEvent(QEvent::HoverEnter, item, scenePos, lastScenePos, modifiers, accepted);
+                }
             }
             return true;
         }
diff --git a/src/declarative/items/qsgcanvas_p.h b/src/declarative/items/qsgcanvas_p.h
index 20fc332e1b..d26b311e59 100644
--- a/src/declarative/items/qsgcanvas_p.h
+++ b/src/declarative/items/qsgcanvas_p.h
@@ -117,11 +117,11 @@ public:
     bool deliverHoverEvent(QSGItem *, const QPointF &scenePos, const QPointF &lastScenePos, Qt::KeyboardModifiers modifiers, bool &accepted);
     bool sendHoverEvent(QEvent::Type, QSGItem *, const QPointF &scenePos, const QPointF &lastScenePos,
                         Qt::KeyboardModifiers modifiers, bool accepted);
-    void clearHover();
+    bool clearHover();
     void deliverDragEvent(QSGDragEvent *);
     bool deliverDragEvent(QSGItem *item, QSGDragEvent *);
 
-    QDeclarativeGuard<QSGItem> hoverItem;
+    QList<QSGItem*> hoverItems;
     enum FocusOption {
         DontChangeFocusProperty = 0x01,
     };
diff --git a/src/declarative/items/qsgitem.cpp b/src/declarative/items/qsgitem.cpp
index 043c568a82..ef77bfda02 100644
--- a/src/declarative/items/qsgitem.cpp
+++ b/src/declarative/items/qsgitem.cpp
@@ -1161,6 +1161,8 @@ void QSGItemPrivate::initCanvas(InitializationState *state, QSGCanvas *c)
             c->itemsToPolish.remove(q);
         if (c->mouseGrabberItem == q)
             c->mouseGrabberItem = 0;
+        if ( hoverEnabled )
+            c->hoverItems.removeAll(q);
     }
 
     canvas = c;
@@ -3021,8 +3023,21 @@ void QSGItem::setAcceptHoverEvents(bool enabled)
     Q_D(QSGItem);
     d->hoverEnabled = enabled;
 
-    if (d->canvas && d->hoverEnabled && !d->canvas->hasMouseTracking())
-        d->canvas->setMouseTracking(true);
+    if (d->canvas){
+        QSGCanvasPrivate *c = QSGCanvasPrivate::get(d->canvas);
+        if (d->hoverEnabled){
+            if (!d->canvas->hasMouseTracking())
+                d->canvas->setMouseTracking(true);
+            if (isUnderMouse())
+                c->hoverItems.prepend(this);
+                c->sendHoverEvent(QEvent::HoverEnter, this, c->lastMousePosition, c->lastMousePosition,
+                        QApplication::keyboardModifiers(), true);
+        } else {
+            c->hoverItems.removeAll(this);
+            c->sendHoverEvent(QEvent::HoverLeave, this, c->lastMousePosition, c->lastMousePosition,
+                    QApplication::keyboardModifiers(), true);
+        }
+    }
 }
 
 void QSGItem::grabMouse() 
diff --git a/src/declarative/items/qsgmousearea.cpp b/src/declarative/items/qsgmousearea.cpp
index ac577a4810..88a617fd71 100644
--- a/src/declarative/items/qsgmousearea.cpp
+++ b/src/declarative/items/qsgmousearea.cpp
@@ -834,8 +834,6 @@ void QSGMouseArea::setHoverEnabled(bool h)
 
     setAcceptHoverEvents(h);
     emit hoverEnabledChanged();
-    if (d->hovered != isUnderMouse())
-        setHovered(!d->hovered);
 }
 
 bool QSGMouseArea::hovered() const
diff --git a/tests/auto/declarative/qsgmousearea/data/hoverPropagation.qml b/tests/auto/declarative/qsgmousearea/data/hoverPropagation.qml
new file mode 100644
index 0000000000..c47c794132
--- /dev/null
+++ b/tests/auto/declarative/qsgmousearea/data/hoverPropagation.qml
@@ -0,0 +1,54 @@
+import QtQuick 2.0
+
+Item{
+    width: 400
+    height: 200
+    property bool point1: ma2.containsMouse && !ma1.containsMouse
+    property bool point2: ma3.containsMouse && ma4.containsMouse
+    Rectangle{
+        width: 200
+        height: 200
+        color: ma1.containsMouse ? "red" : "white"
+        MouseArea{
+            id: ma1
+            hoverEnabled: true
+            anchors.fill: parent
+        }
+        Rectangle{
+            width: 100
+            height: 100
+            color: ma2.containsMouse ? "blue" : "white"
+            MouseArea{
+                id: ma2
+                hoverEnabled: true
+                anchors.fill: parent
+            }
+        }
+    }
+
+    Item{
+        x:200
+        Rectangle{
+            width: 200
+            height: 200
+            color: ma3.containsMouse ? "yellow" : "white"
+            Rectangle{
+                width: 100
+                height: 100
+                color: ma4.containsMouse ? "green" : "white"
+            }
+        }
+        MouseArea{
+            id: ma3
+            hoverEnabled: true
+            width: 200
+            height: 200
+            MouseArea{
+                id: ma4
+                width: 100
+                height: 100
+                hoverEnabled: true
+            }
+        }
+    }
+}
diff --git a/tests/auto/declarative/qsgmousearea/tst_qsgmousearea.cpp b/tests/auto/declarative/qsgmousearea/tst_qsgmousearea.cpp
index 8e711e6ceb..e9788cd147 100644
--- a/tests/auto/declarative/qsgmousearea/tst_qsgmousearea.cpp
+++ b/tests/auto/declarative/qsgmousearea/tst_qsgmousearea.cpp
@@ -75,6 +75,7 @@ private slots:
     void testQtQuick11Attributes();
     void testQtQuick11Attributes_data();
     void hoverPosition();
+    void hoverPropagation();
 
 private:
     QSGView *createView();
@@ -741,6 +742,31 @@ void tst_QSGMouseArea::hoverPosition()
     delete canvas;
 }
 
+void tst_QSGMouseArea::hoverPropagation()
+{
+    //QTBUG-18175, to behave like GV did.
+    QSGView *canvas = createView();
+    canvas->setSource(QUrl::fromLocalFile(SRCDIR "/data/hoverPropagation.qml"));
+
+    QSGItem *root = canvas->rootObject();
+    QVERIFY(root != 0);
+
+    QCOMPARE(root->property("point1").toBool(), false);
+    QCOMPARE(root->property("point2").toBool(), false);
+
+    QMouseEvent moveEvent(QEvent::MouseMove, QPoint(32, 32), Qt::NoButton, Qt::NoButton, 0);
+    QApplication::sendEvent(canvas, &moveEvent);
+    QCOMPARE(root->property("point1").toBool(), true);
+    QCOMPARE(root->property("point2").toBool(), false);
+
+    QMouseEvent moveEvent2(QEvent::MouseMove, QPoint(232, 32), Qt::NoButton, Qt::NoButton, 0);
+    QApplication::sendEvent(canvas, &moveEvent2);
+    QCOMPARE(root->property("point1").toBool(), false);
+    QCOMPARE(root->property("point2").toBool(), true);
+
+    delete canvas;
+}
+
 QTEST_MAIN(tst_QSGMouseArea)
 
 #include "tst_qsgmousearea.moc"